Screening for detection of wild oat biotypes resistant to fenoxaprop-P-ethyl from Mexico

Avena is one of the world’s most important genera resistant to herbicides. Suspected resistant biotype and susceptible biotype of Avena fatua were tested by screening to confirm the resistance to fenoxaprop-P-ethyl from Mexico. Suspected-resistant population was collected in wheat fields after the herbicide failed to control wild oat and the susceptible one was collected from a field with no herbicide application. Petri dish experiments were performed using different fenoxaprop-P-ethyl concentrations (0, 1, 5, 10 and 40 mM). Experiments were arranged in a completely randomized design with ten replicates. Plumule length in both biotypes decreased as fenoxaprop-P-ethyl concentration increased. However, there was a different response between the R and S biotypes. The EC50 for the resistant biotype was 3.3 mM while for the susceptible biotype was 9.3 mM, showing that the resistant biotype tolerated herbicide concentration approximately three times higher than the susceptible biotype. The results confirm the presence of Avena fatua resistant to fenoxaprop-P-ethyl in Mexico.